The present invention relates to an optical fiber sensor system.
Japanese Unexamined Patent Publication No. 2008-309776 describes an optical fiber vibration sensor including a light source, a light receiver, a light branching and coupling portion having a polarizer and two couplers, and a fiber loop portion. The light source and the light branching and coupling portion are coupled optically, and light of which a light polarization state is controlled such that it is uniform by the polarizer is output to the fiber loop portion through the light branching and coupling portion. Clockwise light and counterclockwise light are propagated to the fiber loop portion. The clockwise light and the counterclockwise light are recombined and interfere in the light branching and coupling portion, and interference light is obtained. The interference light is received by a light receiver and converted into an electrical signal. When the acoustic signal is applied to the fiber loop, a different phase difference is imparted to the clockwise light and the counterclockwise light and an interference state of the interference light is changed. Stress applied to the fiber loop is detected by the light receiver receiving the interference light of which the interference state has been changed.